Electrical generation and distribution.



Patented Nov. 4, I902.

W. STANLEY &. J. F. KELLY. ELECTRICAL GENERATION AND DISTRIBUTION.

(Applicution filed June 25, 1902.

2 Sheets-Shoo! I.

(No Model.)

wiiueooa No. 7I2,6l4. v Patented Nov. 4, I902. W. STANLEY '& J. F.KELLY. ELECTRICAL GENERATION AND DISTRIBUTION.

(Applicstion filed Jun. 25, 1902.)

(No lodol.) 2 Sheets-Shea! 2.

Jtan/eg,

John

UNITED STATES PATENT OFFICE.

\VILLIAM STANLEY, OF GREAT HARRINGTON, AND JOHN F. KELLY, OF PITTSFIELD,MASSACHUSETTS.

ELECTRICAL GENERATION AND DISTRIBUTION.

SPECIFICATION forming part of Letters Patent No. 712,614, dated November4, 1902.

Application filed June 25, 1902.

To all who/'11, it may concern.-

Be it known that W8,WILLIAM STANLEY, residing at Great Harrington, andJOHN F. KELLY, residing at Pittsfield, Massachusetts, citizens of theUnited States, have invented certain new and useful Improvements inElectrical Generation and Distribution, of which the following is afull, clear, and exact description.

Our invention relates to improvements in the generation of anddistribution of electrical energy by alternating currents, and has forits object the production and distribution of currents of that class insuch a manner that the pressure is automatically regulated with- 1 outregard to the nature of the load upon the mains. This is a greatadvance, since in the present transformer systennin which aconstant-potential generator is used for supplying transformers inmultiple arc with lamps in multiple on their secondaries, it isnecessary that the transformers should not only be made to be used withthe potential upon the mains, but they must be adapted to the generatorso as to have an insignificant leakage or magnetizing current at noload. It is well known that any closed magnetic-circuit transformerwhich will not burn up on account of core loss when connected toconstant-potential mains will be adapted to the generator, so as to havesuch insignificant leakage-current, and that if the primary andsecondary coils are sandwiched or intermingled, so that the turns areall in the same homogeneous magnetic atmosphere, approximate constancyof potential at the secondary terminals within limits is inherent andthat the limit at which the drop in secondary potential exceeds anygiven amount, or, in other words, the capacity of the transformerdepends only upon the resistances of the primaryand secondarycoils, sothat if the crosssection of the wire is increased the capacity will beincreased and the approximation to constancy of potential at thesecondary terminals for any given load will also be increased. In openmagnetic -circuit trans formers or other similar phase-displacingdevices, however, there is always a large magnetizing-current which lagsbehind its electromotive force, disturbing the ordinary gen- Serial No.113,061. (No model.)

erator and reducing its output by demagnetizing its field-magnet. Thesetransformers, therefore, although they may be made to withstand thepotential of the mains, are not adapted to the ordinarya1ternatingcurrent generator and cannot be satisfactorily used in thesystems at present in use.

The purpose of our invention is to generate and distribute alternatingcurrents, so that when the currents supplied lag or lead because of thenature of the load such lagging or leading currents instead ofdisturbing the generator shall automatically act to maintain constantthe potential on the mains. The advantages of such generation anddistribution will be manifest to those who are familiar with the art asnow practiced, since it does away with the disturbing efiects oftranslating devices, such as motors and open-circuit transformers, whichare very troublesome in ordinary systems.

The principle upon which our improvement depends is that of theinductive action of one alternating current upon another, the two beingrelated as primary and secondaryviz., that if the two circuits beproperly disposed if the secondary current lags positively it will reactupon the primary circuit, increasing the primary current to the extentnecessary to maintain the magnetic flux, and if the secondary has anegative lag then it will react upon the primary circuit, reducing theprimary current to the amount necessary to maintain the flux.

In carrying out our invention the lagging or leading currents are thearmature-currents, which are made to act upon field-energizing circuitscarrying alternating currents. The resistance of the field-energizingcoils is made very low, so that the electromotive forces applied to theterminals of the energizing-coils and the counter-electromotive forcesset up therein will always be substantially equal, and the variation ofcurrent in the energizing-circuits will be controlled practically onlyby the reaction of the armaturecurrents.

The following is a description of a system for carrying outourimprovements, reference being had to the accompanying drawings, in whichFigure 1 isa side elevation of the generator. Fig. 2 is a diagrammaticview of the system employing the generator and various translatingdevices supplied thereby. Figs. 3, 4, 5, 6, and 7 are diagrammatic.

Referring more particularly to the drawings, A is a generator having anarmature B with its induced windings b of such low resistance as to makethe full-load resistance drop always practically negligible under normalworking conditions.

O is a field structure having windings c c supplied with multiphasealternating currents from the small substantially-constantpotentialmultiphase exciter D, the windings c 0 being so disposed that themultiphase eXciter-currents produce in the field C revolving magneticpoles or fields of force outtingthearmature-conductors b. These windingsc c are of such low resistance that in normal operation their appliedand counter electromotive forces are always practically equal. If thedesired frequencyof the generator is, say, sixty alternations persecond, the frequency of the emitter D is made muchlesssayaboutfouralternations per secondproducing magnetic fieldsrevolving four times per second. Power is then applied to thegenerator-shaft E, so as to revolve the field structure 0 at a constantspeed of sixty minus four, or fifty-six times a second, thus producing arotating field revolving sixty times a second, due partly to themechanical rotation of the field structure C relatively to the armatureand partly to the rotation of the magnetic poles or fields relative tothe field structure.

The resistance of the field and the eXciter circuits, being made low, asabove described, does not interfere materially with the flow of thealternating currents therein, but leaves them to be controlled by theinductance of the field as modified by the reaction of thearmature-currents. The inductances of the fieldcircuits must at alltimes be so high relatively to the resistances that they may determinethe exciter-currents. The mutual induction between the armature-coilsand the field-coils should also be high, so that the armature-currentsshall modify the inductances of the-fieldcircnits properly, which weaccomplish by placing the armature-coils as close to the fieldcoils aspossible, constructing the field, as shown, with its windingsdistributed upon the surface of its peripheries and making the magneticcircuit of very low reluctance. Now with such an arrangement if thepotential delivered by the exciter D is constant the potential deliveredby the generator is constant so long as the applied and counterelectromotive forces of the energizing-circuits are substantially equalindependently of any lagging or leading of the current in thearmature-coils, being determined solely by the electromotive force ofthe multiphase exciter. Within the limits of operation no manipulationor variation of the electromotive force of the exciter is necessary, asthe exciter and generator, reacted upon by the currents in the mains,will automatically adjust the value of the exciting-currents to producea constant electrom o'tive force at the main generator-terminals.ThechangesintheeXciting-currents are instantaneous, and consequently theelectromotive force of the main generator never varies because ofchanges in the power factor of the circuits which it supplies. Theactions which produce this result may be explained as follows: Supposethe currents in the armature do not lagviz., are in phase with theelectromotive force. of the revolving field structure will lie as shownin Fig. 6, and four-sixtieths of the electromotive force andfour-sixtieths of the current willbe due to the movement relative to thefield structure of the field or pole produced by the multiphaseexciting-currents, and fifty-six sixtieths will be due to the rotationof the field structure. If now the current in the armature-coils lagsthrough some angle-say thirty degreesit tends to demagnetize thefield-magnet. The revolving field structure will, however, have beenadvanced thirty degrees of the armature-electromotiveforce period beforethe current in the armature-coils attains its maximum value, and thearmature and field circuits willbe more nearly opposite each otherviz.in better mutualinduction-as shown in Fig.7. The field-circuits willthen be more powerfully reacted upon by the armature-current, allowingmore primary current to flow, and so keeping up the value of the fieldcutting the armature-circuit. In other words,the armature-circuit is sorelated to the field-circuits that it is acted upon as a secondary bythe alternating currents in the field, and when the current in the mainslags reduces the inductance of the field-circuits, thereby permittingmore energizing-current to flow and maintaining the field magnetism.This is in marked contrast with the ordinary system in which the laggingcurrent simply demagnetizes the field of the generator, the

' energizing-current not being afiected by any reduction of inductance,and therefore not increasing, so as to counteract the demagnetizingeifect. In our improvement if the current leads instead of laggingpositively such lead places the armature-coil in a position to assist orincrease the magnetizing eifect of the field-windings by reacting uponthem as a primary, and consequently increases the inductance of theeXciter-circuit and reduces the exciter currents correspondingly, thusagain maintaining the field constant and preventing a change in theelectromotive force at the main generator-terminals' In the system shownin Fig. 2, A is the generator, having thesubstantially-constant-potential multiphase exciter D and the circuits MM leading therefrom, with various translating devices in multiple arcto.wit, an open-circuit transformer F, with lamps in parallel on itssecondary, a closed magnetic Then the pole or field IIOcircuit-transformer G, with lamps in parallel on its secondary, atransformer II, with lamps in series on its secondary, and analternatint current ind notion-motor I-\Vliich devices it has neverbefore been possible to use on the same generator without expensive. andunsatisfactory local devices for preventing the evil effects due to thelagging currents which are produced because of the phase-displacingproperties of open magneticcircuit transformers and similar apparatusand the circuits of which they form a part. With our improvement,however, lagging or leading currents do not produce any such evileffects, and therefore no adaptation, such ashas heretofore beennecessary, need exist; but the devices can be used indiscrimately solong as they are made to be used with the voltage and frequencyemployed.

The low frequency of the exciter permits the use of a small exciter, andthus makes a practicable system. The frequency should be as low as iscompatible with the desired regulation. The self-induction of thefieldexciting coils must be high relatively to their resistance, thoughnot necessarily high in an absolute sense, so that, as in an ordinarytransformer, the flow of current will be made to vary inversely with theinductance and be substantially independent of the resistance. Thedesired results are attained by energizing the generator by impressingalternating electromotive forces of low frequency on the field-coilterminals and maintaining at these terminals con nter electromotiveforces always substantiallyequal-totheimpressed, and from the currentsthus produced and by motion due to external mechanical power inducingcurrents of normal frequency in the armature, which, if they lag orlead, react so as to control the flow of the low-frequencyenergizing-currents, so as to maintain a substantially constant inducing-field and consequent constantpotential at the generator-terminals.

Such generation and distribution as above described is of peculiar valuein connection with systems of high-tension long-distance transmission,in which the power factor varies very greatly with the load.

What we claim is- 1. The method of producing alternating currents ofnormal frequency and constant potential, which consists in producingalternating currents of very low frequency and inducing from them by theaid of mechanical motion currents of normal frequency, and controllingthe flow of the low-frequency currents by the reaction of the inducedcurrents so as to maintain a substantially constant inducing-field.

2. The method of generating and distributing electrical energy byalternating currents which consists in applying to the terminals of aplurality of field-circuits alternating currents of differing phase,maintaining in said circuits counter electromotive forces substantiallyequal to the applied under all normal conditions, and causing said fieldto act upon a revolving-armatu re circuit to induce alternating currentstherein.

The method of producing alternating currents of normal frequency andconstant electromotive force which consists in applying to the terminalsof field-circuits alternating electromotive forces of very lowfrequency, maintaining in said circuits a counter electromotive forcesubstantiallyequal to the applied electromotive force under all normalconditions, and inducing from the cu rrents thus produced by the aid ofmechanical motion currents of the normal frequency and controlling theflow of the current due to the low-frequency electromotive forces by thereaction of the induced currents so as to maintain a substantiallyconstant indueing-field.

4. The method of maintaining constant magnetization in analternating-current generator which consists in exciting the field ofthe generator by very-low-frequency polyphase alternating currentsinducing by the field thus produced and by mechanical-rotationalternating currents of normal frequency and causing the high-frequencycurrents in case they lag or lead to react so as to vary theexciting-currents to the proper amount to maintain the field constant.

5. The method of maintaining constant magnetization in analternating-current generator which consists in exciting the field ofthe generator by very-low-frequency polyphase alternating currentsinducing by the field thus produced and by mechanical rotationalternating currents of normal frequency and causingsaidnormal-frequency currents to react upon the exciting-currents, theapplied and counter electromotive forces in the fieldcircuits beingmaintained substantially equal under all normal conditions.

6. Themethodofproducingalternatingcurrents of normal frequency andconstant potential, which consists in producingsubstantially-constant-potential alternating currents of verylowfrequency and inducing from them by the aid of mechanical motioncurrents of normal frequency, and controlling the flow of thelow-frequency currents by the reaction of the induced currents so as tomaintain a substantially-constant inducing-field.

7. The method of generating and distributing electrical energy byalternating currents which consists in applying to the terminals of aplurality of field-circuits substantially-constant-potential alternatingcurrents of differing phase, maintaining in said circuits counterelectromotive forces substantially equal to the applied under all normalconditi0ns,and causing said field to act upon arelatively-revolving-armature circuit to induce alternating currentstherein.

8. The method of producing alternating currents of normal frequency and.constant electromotive force which consists in applying to the terminalsof field-circuits substantiallyconstant-potential alternatingelectromotive forces of Very low.frequency, maintainingin said circuitsa counter electromotive force substantially equal to the appliedelectromotive force under all normal conditions, and inducing from thecurrents thus produced by the aid of mechanical motion currents of the"normal frequency and controlling the flow of the current due to thelow-frequency electromotive forces by the reaction of the inducedcurrents so as to maintain a substantiallyconstant inducing-field.

9. The method of maintaining constant magnetization in analternating-current generator which consists in exciting the field ofthe generator by very-low-frequcncy, sub-

